The present invention relates to containers, and more particularly, to paperboard containers having stacking tabs and mating openings for maintaining adjacent containers in an aligned, stacked arrangement.
Various types of stacking tabs are known for use with paperboard containers, and especially produce trays. These tabs help maintain the alignment of stacked containers during shipping and also contribute to maintaining the integrity of the containers as a single unit.
In prior designs, stacking tabs are generally formed along an upper edge of a tray""s end wall. A lower opening is formed in the tray bottom surface to receive the stacking tab of an adjacent underlying tray.
Known stacking tabs having a number of disadvantages. Generally, the problem has been in finding ways to increase the strength of the tabs without undue losses in container production efficiency or increases in material waste. Some designers include metal stacking wires to improve their strength, while others use a folded-over double-ply paperboard tab. The insertion of metal stacking wires is a time-consuming task and not efficient for large-scale container production projects. The use of folded-over double-ply paperboard tabs is helpful, but not every container needs or can be cost-effectively produced with double-walled sides.
In one arrangement, described in U.S. Pat. No. 5,390,847, a tray is provided with a separate lid that includes secondary, triangular stacking tabs. When assembled these lid stacking tabs are exterior to the tray""s end wall stacking tabs. In the ""847 arrangement, however the end wall stacking tabs have a tendency to catch on objects and fold over easily. This ruins the tabs and renders them unfit for maintaining container alignment. While the lid stacking tabs are helpful to support the end wall tabs, they are insufficient to keep the edges of the end wall tabs from collapsing, either inward or outward.
Thus, a need exists for a container with side wall stacking tab arrangements that are much more resistant to folding and that can be easily and inexpensively mass produced. Ideally, the stacking tabs would be available for use with a number of known container shapes and sizes, and particularly for use with produce trays.
A combined stacking tab is provided for use with a container having a containment portion and a lid. The containment portion includes a lateral panel and an upright wall. The upright wall includes an upper edge with a stacking tab. The lid also includes a lateral panel and an upright wall connected to the lateral panel. A lid stacking tab is cut from portions of the lid lateral panel at its connection to the lid upright wall, thereby resulting in an opening in the lid lateral panel. As erected, the lid stacking tab remains in the plane of the lid upright wall, with the containment portion stacking tab being located within the opening of the lid lateral panel. The combination of the containment portion stacking tab and the lid stacking tab form a combined stacking tab of at least double-ply material thickness.